"An unconference is a conference where the content of the sessions is driven and created by the participants, generally day-by-day during the course of the event, rather than by a single organizer, or small group of organizers, in advance." 
"First, you take the people who used to be the audience and give them a promotion. They’re now participants. Their job is to participate, not just to listen and at the end to ask questions. Then you ask everyone who was on stage to take a seat in what used to be the audience. Okay, now you have a room full of people, what exactly are they supposed to do? Choose a reporter, someone who knows something about the topic of discussion (yes, there is a topic, it’s not free-form) and knows how to ask questions and knit a story together."
= An unconference is a facilitated participant-driven face-to-face conference around a theme or purpose. 
From the Wikipedia article at http://en.wikipedia.org/wiki/Unconference
"An unconference is a conference where the content of the sessions is driven and created by the participants, generally day-by-day during the course of the event, rather than by a single organizer, or small group of organizers, in advance. To date, the term is primarily in use in the geek community. Unconference processes like Open Space Technology, however, have been around for over 20 years in other contexts.
The term unconference first appeared amongst techies in an announcement for the annual XML developers conference in 1998. More recently the term was used by Lenn Pryor when discussing BloggerCon and was popularized by Dave Winer, the organizer of BloggerCon, in an April 2004 writeup. Winer's unconference is a discussion leader with a topic moving a microphone amongst a large audience of 50 to 200 people.
Open Space Technology is an energizing and emergent way to organize an agenda for a conference. Those coming to the event can post on a wiki ahead of time topics they want to present about or hope others will present about. The wiki can also be used to share who is coming because it is the attendees who have a passion to share that contribute to the event and will make it great.
The event begins with face to face schedule making which allows for emerging developments in the rapidly moving technology field to be covered. The opening includes time for attendees to introduce themselves and orient to the whole group. Participants are invited to write their name and session topic on an 8.5×11 piece of paper. They announce the title of their session to the whole room and then post it on a schedule on the wall. Once all the sessions have been posted, the community can stand in front of the schedule wall and decide which sessions they would like to attend. Sessions are about an hour long with 15 min breaks. Lunch lasts for about an hour. The day closes with all the participants gathering in a circle in one room and sharing for 20–30 min the highlights of the day." (http://en.wikipedia.org/wiki/Unconference)
Christophe Aguiton and Dominique Cardon:
“The concepts of "spectator-free" and "unconference" didn't appear with the BarCamp, but they are contemporaneous and their emergence is in phase with several other attempts to organise "open" gatherings and public meetings. The term unconference was first used in the late 1990s for techies' meetings (XML developers) and became more popular when it was picked up by the blogger community in 2003 and 2004. The "Open Space Methodology" was theorised by Harrison Owen in 1987 (OWEN, 1997), but two more recent big annual gatherings have been more significant in spreading these new collaborative practises. At the world level, the WSF (World Social Forum) and its local and continental versions are the biggest events using this kind of bottom-up methodology. The forums – which are a gathering of those who reject neo-liberal globalisation - are able to attract up to 150,000 activists, as in Brazil in 2005 (AGUITON & CARDON, 2005). In the Nevada desert, another event, regularly attended by the San Francisco BarCamp core group, is organised each year in the same participatory way: "Burning Man" is an artistic gathering of almost 40,000 people, guided by ten principles; radical inclusion, gifting, decommodification, radical self-reliance, radical self-expression, communal effort, civic responsibility, leaving no trace, participation, and immediacy.
In the BarCamp, as well as in the WSF or Burning Man, there are technical organisers, but the content belongs to and comes from the participants, who build the events in a bottom-up self-organised process. BarCamp, as well as the WSF or Burning Man, is a contact-generating machine. Attending those events, participants don't know what they will discover, but they do know that there will be a chance to present their ideas or proposals, to learn from others, and to get new contacts or to refresh old ones. These are characteristics very similar to those we identified in the use of Web 2.0 applications and services in the first part of this paper. “
Source: The strength of Weak Cooperation. Christophe Aguiton and Dominique Cardon. Communication & Strategies, No. 65, 1st Quarter 2007.
ric Michael Johnson:
"Such participatory organizing has only been possible by using the social media tools that allow those living in different cities, as well as different countries, to interact in a common forum. It should therefore come as no surprise that Science Online, as well as other unconferences that have developed over the years (such as SciFoo, BarCamp, or THATCamp) have been composed largely of people who are tech-savvy. But this is changing and has increasingly been applied to local DIY workshops and skillshares in cities from Brooklyn to Berkeley.
More recently this model of organizing has taken on a political dimension. Politics, after all, is a social activity. In 2009 Chris Hutchins developed the idea for LaidOffCamp in San Francisco, a workshop organized and attended by the newly unemployed to share skills ranging from how to live more simply (and cheaply) to job hunting techniques in a moribund economy. The idea quickly expanded and LaidOffCamp events went on to be organized in New York, Chicago, Miami, Las Vegas, Phoenix, Los Angeles, and Salt Lake City (among others). But last year participatory organizing went mainstream. Occupy Wall Street used this same approach by making the person on stage a facilitator rather than a leader. By accepting proposals from the crowd, amplified by the human microphone in which those nearby repeat each sentence so that others can hear, the facilitator plays the role of fostering consensus on a course of action from the group as a whole. Harkening back to the motto of the populist Louisiana Governor Huey P. Long, crowdsourcing makes “Every man a king, but no one wears a crown.” (http://blogs.scientificamerican.com/primate-diaries/2012/02/02/scio12/)